The lineshape of the plasma-shifted cyclotron resonance is calculated in the two-dimensional system. The nonlocal effect is taken into account to the lowest order and is shown to be extremely small in the usual experimental conditions. When the peak position is close to the subharmonic structure of the usual cyclotron resonance, a coupling splits the peak into two, explaining recent experiments of Theis et al. The agreement with the experiments is satisfactory. © 1978.